ATM Adaptation Layer defines how data is encapsulated into cells and how that data is reconstructed.

AAL1

ATM Adaptation Layer 1 that is used to fix the data rate services in real-time networks, such as voice.

AAL2

ATM Adaptation Layer 2 is intended for services that need real-time support but have VBR, such as compressed video for HDTV.

AAL3/4

ATM Adaptation Layers 3/4 are used for data services.

AAL5

ATM Adaptation Layer 5 is a low-overhead protocol used for LAN services. It is used for the transmission of data such as IP over ATM. The AAL5 is passed to the SAR which segments it into 48 byte cells.

ABR

Available Bit Rate in which data is delivered using the available bandwidth. Flow control is used to provide little or no data loss. A minimum bandwidth may be specified.

ARP

Address Resolution Protocol is an Internet protocol that takes care of translation of L_3 addresses to physical addresses and hide these addresses from the upper layers of the OSI model.

ATM

Asynchronous Transfer Mode that transports small fixed length packets called cells over a high-speed network using multiplexing and switching technology. ATM offers scalable range of speeds beginning at sub-T1 rates and increasing to 622Mbps and beyond. ATM Addresses are 20 bytes long.

BUS

Broadcast & Unknown Server that forwards broadcast, multicast, and unknown data frames to members of the ELAN.

CBR

Constant Bit Rate in which data flows continuous and steady with a guaranteed quality of service. Typically requires greater bandwidth.

CDV

Cell Delay Variation which has to do with jitter.

CIR

Committed Information Rate ensures a "fair" access to the network resources for all users, currently active in the network, via their PVCs.

CLR

Cell Loss Ratio in which the number of cells are lost per connection.

CTD

Cell Transfer Delay which is the time it takes to get across the net.

DLCI

The DLCI is a network address number between 16 and 991 which is used as the address for each end of a PVC.

E.164

Address standard for ISDN.

ELAN

Emulated LAN

EPD

Early Packet Discard

FRS

Frame Relay Service is a data communications service that provides for data connectivity between or among widely distributed end-user locations.

FUNI

Framed User Network Interface designed as a means for ATM devices to use lower speed links such as T-1.

Data Exhange Interface that operates in three modes: 1A for AAL5 providing up to 1,023 VCs, 1B operates with AAL3/4 and AAL5 providing up to 1,023 VCs, and mode 2 operates with AAL3/4 and AAL5 providing up to 16,777,215 VCs.

Frame

Variable-length packet of data used by traditional LANs such as Ethernet and Token Ring as well as WAN services such as X.25 or Frame Relay.

HEC

Header Error Control

IDP

Initial Domain Part

IEEE 802

Addressing for LANs.

ILMI 4.0

Interim Link Management Interface that defines the interfaces between public and private networks and assists in auto-registration of ATM devices.

ITU

International Telecommunications Union

LANE

Local Area Network Emulation that provides the functionality of a single LAN segment (IEEE 802.5 Token Ring), or IEEE 802.3 Ethernet).

LEC

LANE Emulation Client that presents a MAC-level interface to the higher layer protocols and implements LUNI when communicating with other components on the ELAN.

LANE Server that maintains a cache of MAC-to-ATM addresses and is an address resolution server.

LIS

Logically Independent Subnetworks

LUNI

LAN User Network Interface

MPLX

Multi-Protocol Labeling standard that routes packets from subnet to subnet using a label to simplify packet forwarding.

MPOA

Multiple Protocol of ATM that enables layer-three protocols such as IP and IPX to operate directly over ATM. MPOA is responsible for five major operations: configuration, discovery, target resolution, connection management, and data transfer.